The official recommendation for how much water to store per person comes from FEMA and the American Red Cross: 1 gallon per person per day for a 3-day minimum supply. But that’s a floor, not a target — and several factors can raise your actual requirement significantly.
The FEMA Baseline: 1 Gallon Per Person Per Day
The 1-gallon figure breaks down as follows:
- Drinking: ~0.5 gallons (roughly 2 liters, the standard hydration recommendation)
- Cooking and food preparation: ~0.25 gallons
- Basic sanitation (hand washing, oral care): ~0.25 gallons
Note what this does NOT include: showering, laundry, dishwashing, or toilet flushing (which uses municipal pressure, not your stored supply, in most cases). The 1-gallon figure is survival-level minimums for the duration of an emergency.
When 1 Gallon Per Day Isn’t Enough
The baseline assumes average adults in a temperate environment doing minimal physical activity. Adjust upward in these situations:
Hot Weather / High Temperatures
In temperatures above 90°F without air conditioning, the human body needs significantly more water. Add 0.5–1 gallon per person per day in extreme heat. During the 2021 Pacific Northwest heat dome, some regions saw temperatures exceeding 108°F for multiple days — standard 1-gallon recommendations were dangerously insufficient for many people.
Physical Activity
If an emergency situation requires physical labor (hauling supplies, cleaning up after a flood or storm), hydration needs increase substantially. Add 0.5 gallons per active hour of work per person.
Medical Conditions
- Kidney conditions: may require increased fluid intake; consult your physician
- Diabetes: increased urination means increased hydration needs
- Certain medications: diuretics, lithium, and others affect hydration needs
Children
Children actually need less water per day than adults, but their needs per pound of body weight are higher, and dehydration affects them faster. Budget 0.5–0.75 gallons per child under 12.
Nursing Mothers
Lactation increases water needs by approximately 0.5–1 liter per day. Add 0.25–0.5 gallons per nursing mother.
Pets
- Large dog (50+ lbs): 0.5 gallons/day
- Medium dog (25–50 lbs): 0.33 gallons/day
- Small dog (under 25 lbs): 0.2 gallons/day
- Cat: 0.1 gallons/day
Storage Targets by Household Size
| Household | 3-Day Min | 2-Week Recommended | Space Required (5-gal jugs) |
|---|---|---|---|
| 1 person | 3 gallons | 14 gallons | 3 jugs |
| 2 people | 6 gallons | 28 gallons | 6 jugs |
| 2 people + dog | 7.5 gallons | 35 gallons | 7 jugs |
| Family of 4 | 12 gallons | 56 gallons | 12 jugs |
3-Day vs. 2-Week Supply: Which Should You Target?
3-day supply (FEMA minimum): Designed for short-term events like utility outages and minor storms. For most apartment dwellers in urban areas, this is a reasonable starting point. Utility outages in US cities rarely exceed 72 hours outside of major disasters.
2-week supply (extended preparedness): Recommended by FEMA and Red Cross for households in areas prone to natural disasters (hurricanes, earthquakes, major winter storms). A 2-week supply for one person is just 14 gallons — three 5-gallon jugs — which fits in virtually any apartment closet.
Our recommendation: Start with a 3-day supply immediately, then build toward a 2-week supply over the next few months. The incremental cost is low ($2–5 per gallon for properly packaged water), and the peace of mind is significant.
How to Build Your Supply Gradually
You don’t need to buy everything at once. A $5/week approach:
- Week 1: Buy two 1-gallon jugs ($2) and a WaterBOB ($25)
- Week 2: Buy a 5-gallon water jug and a pump ($12)
- Week 3: Add three more 1-gallon jugs ($3)
- Week 4: Fill your WaterBOB (free — uses your tap water)
Within a month and for under $50, you have a substantial water supply that covers a 2-week emergency for one person.
Water Storage Cost Breakdown
| Option | Gallons | Cost | Cost per Gallon |
|---|---|---|---|
| Tap water in HDPE jugs | Any | $8–15 per jug | $0.01–0.05 |
| WaterBOB (bathtub) | 100 | $30 | $0.30 |
| Commercial 1-gallon jugs | 1 each | $1–2 each | $1–2 |
| 5-gallon water delivery | 5 | $8–12 | $1.60–2.40 |
Filling your own food-grade containers from the tap is by far the most economical option. Municipal tap water is safe to store (treat with bleach if storing longer than 6 months) and costs essentially nothing.